如何使用优化权重训练模型？

Question

我正在研究模型参数的优化。从广义上讲，我训练了具有某种结构的模型的权重。我现在使用这个权重来训练另一个完全相同结构的模型。但是我无法获得相同的准确度，在第一个时代也没有相同的准确度。

以下代码解释了整个问题。

from __future__ import print_function

from keras.preprocessing import sequence
from keras.models import Sequential
from keras.layers import Dense, Dropout, Activation
from keras.layers import Embedding
from keras.layers import Conv1D, GlobalMaxPooling1D
from keras.datasets import imdb

# set parameters:
max_features = 5000
maxlen = 400
batch_size = 32
embedding_dims = 50
filters = 250
kernel_size = 3
hidden_dims = 250

print('Loading data...')
(x_train, y_train), (x_test, y_test) = imdb.load_data(num_words=max_features)
print(len(x_train), 'train sequences')
print(len(x_test), 'test sequences')

print('Pad sequences (samples x time)')
x_train = sequence.pad_sequences(x_train, maxlen=maxlen)
x_test = sequence.pad_sequences(x_test, maxlen=maxlen)
print('x_train shape:', x_train.shape)
print('x_test shape:', x_test.shape)

print('Build model...')
model = Sequential()

# we start off with an efficient embedding layer which maps
# our vocab indices into embedding_dims dimensions
model.add(Embedding(max_features,
                    embedding_dims,
                    input_length=maxlen))
model.add(Dropout(0.2))

# we add a Convolution1D, which will learn filters
# word group filters of size filter_length:
model.add(Conv1D(filters, kernel_size, padding='valid',    activation='relu', strides=1))
# we use max pooling:
model.add(GlobalMaxPooling1D())

# We add a vanilla hidden layer:
model.add(Dense(hidden_dims))
model.add(Dropout(0.2))
model.add(Activation('relu'))

# We project onto a single unit output layer, and squash it with a sigmoid:
model.add(Dense(1))
model.add(Activation('sigmoid'))

model.compile(loss='mse',Optimizer='sgd', metrics=['accuracy'])
model.fit(x_train, y_train,batch_size=batch_size,epochs=50, validation_data=(x_test, y_test))

# Extraction of weights
con_weight=model.layers[2].get_weights()[0]
con_bias=model.layers[2].get_weights()[1]

mid_weight=model.layers[4].get_weights()[0]
mid_bias=model.layers[4].get_weights()[1]

pl_weight=model.layers[7].get_weights()[0]
pl_bias=model.layers[7].get_weights()[1]

使用权重训练另一个模型

model1 = Sequential()

# we start off with an efficient embedding layer which maps
# our vocab indices into embedding_dims dimensions
model1.add(Embedding(max_features,
                    embedding_dims,
                    input_length=maxlen))
model1.add(Dropout(0.2))

# we add a Convolution1D, which will learn filters
# word group filters of size filter_length:
model1.add(Conv1D(filters, kernel_size, padding='valid',activation='relu', strides=1,weights=[con_weight,con_bias]))
# we use max pooling:
model1.add(GlobalMaxPooling1D())

# We add a vanilla hidden layer:
model1.add(Dense(hidden_dims,weights=[mid_weight,mid_bias]))
model1.add(Dropout(0.2))
model1.add(Activation('relu'))

# We project onto a single unit output layer, and squash it with a sigmoid:
model1.add(Dense(1,weights=[pl_weight,pl_bias]))
model1.add(Activation('sigmoid'))
model1.trainable=False
model1.compile(loss='mse', optimizer='sgd', metrics=['accuracy'])
model1.fit(x_train, y_train, batch_size=batch_size, epochs=1,
validation_data=(x_test, y_test))

Answer 1

嵌入确实有权重，你会忘记它们。

但你的模型是相同的，只是：

model1.set_weights(model.get_weights())